Abrasive sheet and process of making the same



Jan. 7, 1936. o. s. BUCKNER ABRASIVE SHEET AND PROCESS OF MAKING THE SVAHE l Filed Oct. 3, 1928 Patented Jan. 7, 1936 UNITED sTATEs PATENT OFFICE ABRASIVE SHEET AND PROCESS F MAKING THE SAME Application October 3, 1928, Serial No. 310,058

8 Claims.

This invention relates to a modified form of the invention disclosed in my issued Patent 1,930,788, dated October 17, 1933, which relates to abrasive or attrition tools and methods of making the same, and in the construction of which the elongated grains of abrasive material are electrically positioned, so that they are bonded in approximately perpendicular relation to the working face of the tool.

The present invention relates, more specifically to an application of the generic invention to the production of abrasive or attrition sheets and has for its object the production of a sheet of this character which has the essential characteristics of the abrasive tools previously disclosed in said application and to a method of making the same which will be commercially successful.

I accomplish these objects in the manner hereinafter described and illustrated in the accompanying drawing in which:

Fig. 1 is a side elevation of the essential features of an apparatus which I preferably employ in performing the process of making attrition sheets.

Fig. 2 is a plan view thereof.

Fig. 3 is a sectional view of the finished product.

In carrying out the method of the present invention, in order to make the abrasive material responsive to a magnetic field the abrasive grains are coated with a moist adhesive, then are mixed with finely pulverized iron or steel, and then the adhesive is permitted to dry, so that the grains become coated with a magnetic substance. As some of the grains are likely to adhere to each other, this adhesion must then be broken, and this may be accomplished in various Ways, as by working the same through a wire screen of suit-l able mesh.

As thus prepared, the grains are applied to sheets of suitable material in the following manner; the apparatus which is preferably employed comprising an electromagnet I of straight cylindrical form having the faces of its ends, which form the poles, disposed in planes perpendicular to the central axis of the magnet, the latter being disposed perpendicularly so that said faces Will be horizontal. A table 2 of thin brass, or similar non-magnetic substance is disposed on the top end of the magnet and is provided with a series of suitably arranged guide rolls 3 at its edges beneath which the sheets to be coated are passed. A receptacle 4 having a wire mesh bottom 5 is mounted horizontally directly over the magnet, suitable agitating means 6 being provided for moving the receptacle horizontally` The paper, cloth, or other form of sheet material 1 is coated with a suitable adherent as glue and is then fed over the table 2 beneath rolls 3, to hold it flat, while resting on its surface. The abrasive grains which have previously been coat- 5 ed with the finely divided magnetic dust are placed in the receptacle l, which is then agitated in any suitable manner as by the reciprocating means indicated, so that the grains will be showered onto the adhesively coated sheet as it 10 `is fed over the pole of the magnet. The lines of force of the magnet passing from one pole to the other have principally an approximately vertical direction close to the surface of the sheet and will cause the magnetically coated grains, 15 most of which will be somewhat elongated, or will have one dimension substantially greater than the dimension at right angles thereto, to be polarized as they fall, so that, assuming the pole at the top of the magnet is positive, the nega- 20 tively magnetized ends of the grains will be attractedand the positive ends repulsed, and they will be turned while falling into approximately perpendicular relation to the face of the sheet, with the result that the ends of the elongated 25 grains will penetrate the adhesive coating and will stand upright therein, as indicated in Figs. 1 and 3. As hereinafter explained, it is an' object of the invention to provide a final product in which the grains are substantially all arranged with their major axes substantially perpendicular to the carrier sheet and the further operations are performed to provide a material having these characteristics.

The adhesive will then be permitted to set while still held horizontally and, after this has occurred, thesurplus grains which did not penetrate or touch the adhesive will be shaken off.

The material after these operations have been performed does not have the arrangement of the particles effected by the magnetic field appreciably disturbed. In other words, the resulting abrasive sheet will have practically all the elongated abrasive grains thereon oriented to stand perpendicularly, so that the abrading efficiency 45 of the sheet will be much greaterthan if they lie flatwise of the sheet, on account of the superior cutting qualities of the ends of the abrasive grains, as compared with the sides thereof. The coating of abrasive grains, which is applied to 50 Vthe sheet will also be of greater thickness than it would be if the grains were not positioned on the sheet in perpendicular relation thereto.

I claim:

1. The method. of making attrition sheets 5t' which consists in placing a sheet having an adhesive surface in a magnetic field, so that the lines of force pass approigimately perpendicularly therethrough and showering magnetically coated elongated grains of abrasive material onto said surface.

2. The method of making .attrition sheets which consists in providing a sheet of suitable material with an adhesive surface, showering granular abrasive material containing a substantial portion of elongated grains onto said surface and simultaneously magnetically positioning said elongated grains, as they fall, in approximately perpendicular relation to said surface, so that the end portions of said grains may penetrate said surface and become bonded therein in approximately perpendicular relation thereto.

3. The method of making attrition sheets which consists in covering one surface of a sheet with a suitable adhesive material, passing the sheet while held horizontally with its adhesive side uppermost through the eld of a magnet so that the lines of force thereof pass mainly approximately perpendicularly through the sheet and showering magnetically coated elongated abrasive grains through the eld of the magnet onto said surface.

4. The process of making abrasive material which comprises providing a magnetic eld, feeding a carrier having a surface coated with adhesive through said eld with the lines of force of the field at an angle to the adhesively coated surface of the carrier, causing abrasive particles of a character responsive to magnetic action to be deposited on the carrier, utilizing the eld to arrange the particles on the adhesive surface with.

their major axes substantially perpendicular to the adhesive surface, and conducting the abrasively coated carrier away from` the eld as the particles are deposited thereon.

5. The process of making abrasive material which comprises providing an electromagnetic eld, feeding a carrier having a surface coated with adhesive through said eld with the lines of force of the eld at an angle to the adhesively coated surface of the carrier, causing abrasive particles of a character responsive to electromagnetic action to be deposited on the carrier, utilizing the eld to arrange the particles on the adhesive surface with their major axes substantially perpendicular to the adhesive surface, and

`conducting the abrasively coated carrier away from the eld as the particles are deposited thereon.

6. The process of making abrasive material which comprises providing a magnetic iield,'feed ing a carrier having a surface coated with adfhesive through said field with the lines of force of the field at an angle to the adhesively coated surface of the carrier, causing abrasive particles of a vcharacter responsive to magnetic action to be deposited on the carrier, utilizing the field to 10 arrange the particles on the adhesive surface with their major axes substantially perpendicular to the adhesive surface, conducting the abrasively coated carrier away from the field as the particles are deposited thereon, andperforming the 15 nishing operation to produce a material having the particles with their major axes substantially perpendicular to the adhesive surface.

7. The process of making abrasive material which comprises providing an electromagnetic 20 field, feeding a carrier having a surface coated with adhesive through said eld with the lines of force of the field at an angle to the adhesively coated surface of the carrier, causing abrasive particles of a character responsive to electromag- 25 netic action to be deposited on the carrier, utiliz- Ving the eld to arrange the particles on the ad- .which comprises providing a magnetic eld, feeding a carrier having a surface coated with adhesive through said eld with the lines of force of the field at an angle to the adhesively coated 40 surface of the carrier, causing abrasive particles of a character responsive to magnetic action to be deposited on the carrier, utilizing the eld to arrange the particles on the adhesive surface with their major axes substantially perpendicular to 45 the adhesive surface, conducting the abrasively coated carrier away from the field as the particles are deposited thereon, and permitting the adhesive to set while maintaining the carrier su stantially horizontal. 50

ORELLO S. BUCEIER. 

